fix hanging trainings (#132)

* fix hanging connections

* remove logging

src/allreduce_base.cc

@@ -133,8 +133,6 @@ bool AllreduceBase::Shutdown(void) {
     utils::TCPSocket tracker = this->ConnectTracker();
     tracker.SendStr(std::string("shutdown"));
     tracker.Close();
-    // close listening sockets
-    sock_listen.Close();
     utils::TCPSocket::Finalize();
     return true;
   } catch (const std::exception& e) {
@@ -282,6 +280,7 @@ bool AllreduceBase::ReConnectLinks(const char *cmd) {
   }
   try {
     utils::TCPSocket tracker = this->ConnectTracker();
+    fprintf(stdout, "task %s connected to the tracker\n", task_id.c_str());
     tracker.SendStr(std::string(cmd));
 
     // the rank of previous link, next link in ring
@@ -304,6 +303,8 @@ bool AllreduceBase::ReConnectLinks(const char *cmd) {
     // tracker got overwhelemed and not able to assign correct rank
     if (rank == -1) exit(-1);
 
+    fprintf(stdout, "task %s got new rank %d\n", task_id.c_str(), rank);
+
     Assert(tracker.RecvAll(&num_neighbors, sizeof(num_neighbors)) == \
          sizeof(num_neighbors), "ReConnectLink failure 4");
     for (int i = 0; i < num_neighbors; ++i) {
@@ -317,25 +318,15 @@ bool AllreduceBase::ReConnectLinks(const char *cmd) {
     Assert(tracker.RecvAll(&next_rank, sizeof(next_rank)) == sizeof(next_rank),
            "ReConnectLink failure 4");
 
-    if (sock_listen == INVALID_SOCKET || sock_listen.AtMark()) {
-      if (!sock_listen.IsClosed()) {
-        sock_listen.Close();
-      }
-      // create listening socket
-      sock_listen.Create();
-      sock_listen.SetKeepAlive(true);
-      // http://deepix.github.io/2016/10/21/tcprst.html
-      sock_listen.SetLinger(0);
-      // [slave_port, slave_port+1 .... slave_port + newrank ...slave_port + nport_trial)
-      // work around processes bind to same port without set reuse option,
-      // start explore from slave_port + newrank towards end
-      port = sock_listen.TryBindHost(slave_port + newrank % nport_trial, slave_port + nport_trial);
-      // if no port bindable, explore first half of range
-      if (port == -1) sock_listen.TryBindHost(slave_port, newrank % nport_trial + slave_port);
-
-      utils::Check(port != -1, "ReConnectLink fail to bind the ports specified");
-      sock_listen.Listen();
-    }
+    utils::TCPSocket sock_listen;
+    if (!sock_listen.IsClosed()) {
+      sock_listen.Close();
+    }
+    // create listening socket
+    sock_listen.Create();
+    int port = sock_listen.TryBindHost(slave_port, slave_port + nport_trial);
+    utils::Check(port != -1, "ReConnectLink fail to bind the ports specified");
+    sock_listen.Listen();
 
     // get number of to connect and number of to accept nodes from tracker
     int num_conn, num_accept, num_error = 1;
@@ -423,7 +414,7 @@ bool AllreduceBase::ReConnectLinks(const char *cmd) {
       }
       if (!match) all_links.push_back(r);
     }
-
+    sock_listen.Close();
     this->parent_index = -1;
     // setup tree links and ring structure
     tree_links.plinks.clear();

src/allreduce_base.h

@@ -571,10 +571,6 @@ class AllreduceBase : public IEngine {
   int world_size;
   // connect retry time
   int connect_retry;
-  // backdoor listening peer connection
-  utils::TCPSocket sock_listen;
-  // backdoor port
-  int port = 0;
   // enable bootstrap cache 0 false 1 true
   bool rabit_bootstrap_cache = false;
   // enable detailed logging

src/allreduce_robust.cc

@@ -708,9 +708,6 @@ bool AllreduceRobust::CheckAndRecover(ReturnType err_type) {
           return true;
         }
       }
-      // print on tracker to help debuging
-      TrackerPrint("[ERROR] rank " + std::to_string(rank) + "@"+
-          host_uri + ":" +std::to_string(port) + " timeout\n");
       _error("[%d] exit due to time out %d s\n", rank, timeout_sec);
       return false;
     });